Apparatus and method for forming plastic containers from plastic parisons using pressure build-up time regulation

Abstract

A device for forming plastic preforms into plastic containers, comprising a transport device for transporting the plastic preforms to be formed along a predetermined transport path, wherein the transport device has a rotatable transport carrier, on which a plurality of forming stations are arranged, which each have a blow molding device, in the interior of which the plastic preforms can be formed into plastic containers, wherein the forming stations each have an application device, which applies a flowable medium and in particular pressurized air to the plastic preforms, wherein the application device applies a pre-blow pressure, at least one and preferably two intermediate blow pressures, and a final blow pressure to the plastic preforms, and the device has a regulating device, which is adapted and serves to regulate the duration of the pressure build-up time of the at least one intermediate blow pressure. According to the invention, the device has a detection device, which is adapted and serves to detect at least one characteristic value of the plastic containers, wherein the duration of the pressure build-up time of the at least one intermediate blow pressure can be regulated in dependence on this characteristic value of the plastic containers.

Description

Technical Field

[0001] This invention relates to an apparatus and a method for forming plastic preforms into plastic containers. Background Technology

[0002] Such apparatuses and methods have long been known from the prior art. The molding apparatus, and particularly blow molding machines or stretch blow molding machines, have several molding stations containing blow molding devices that form cavities corresponding to the female mold of the plastic container to be manufactured. Typically, a plastic preform is stretched longitudinally within the blow molding device by a stretching rod, and then the preform is formed into a plastic container by applying a flowable medium. The flowable medium is applied at several pressure levels of different pressure stages.

[0003] In the applicant's prior art, it is disclosed that three pressure stages (P1, Pi, P2) are applied to a plastic preform or plastic container, wherein two of these pressure stages (P1 and Pi) preferably use recirculated air entirely or partially. Recently, another (intermediate blow molding) pressure stage (Pi2) has been added. This pressure stage can also use recirculated air.

[0004] By introducing this additional intermediate blow molding stage, various machine inputs can be adjusted. Among these, a so-called sliding regulator, employed in the applicant's prior art, defines the proportion of time spent on intermediate blow molding within the molding stages (intermediate blow molding and final blow molding). Other input schemes, such as input bars or similar, may also be used. A shorter pressurization time in the intermediate blow molding stage allows for earlier application of final blow molding pressure to the plastic preform, which is particularly advantageous for demanding or complex container shapes. However, a longer pressurization time in the intermediate blow molding stage results in a larger volume of pressurized air that can be recycled, potentially leading to saturation at unpredictable locations. Depending on the application, this may prevent achieving the required container quality while simultaneously maximizing recycling potential.

[0005] In addition, the ideal sliding regulator position needs to be manually defined by the operator. To do this, the operator needs to visually assess the container quality and, if there is still "margin" in the pressurized air recovery, further extend the pressurization time in the intermediate blow molding stage to optimize air consumption. This process is repeated until saturation is reached, or until the container quality reaches its lower limit.

[0006] This process is prone to errors and time-consuming, and it cannot guarantee the same container quality across different batches because the sliding regulator needs to be reset each time. The settings also depend on the operator in charge, making it unrepeatable. Summary of the Invention

[0007] Therefore, the object of the present invention is to provide an apparatus and a method for automatically setting or adjusting the boost time. According to the present invention, this object is achieved through the following technical solutions.

[0008] Therefore, the present invention relates to an apparatus for molding a plastic preform into a plastic container, comprising a transport device that transports the plastic preform to be molded along a predetermined conveying path, wherein the transport device has a rotatable transport carrier with a plurality of molding stations, each molding station having a blow molding device in which the plastic preform can be molded into a plastic container, wherein each molding station has an application device that applies a flowable medium, particularly pressurized air, to the plastic preform, wherein the application device applies a pre-blow pressure, at least one and preferably two intermediate blow molding pressures, and a final blow molding pressure to the plastic preform. The apparatus also has an adjusting device adapted for and used to adjust the duration of the pressurization time of at least one intermediate blow molding pressure. Preferably, more than two intermediate blow molding pressures can also be applied to the plastic preform, and thus preferably n intermediate blow molding pressures (Pi1, Pi2, Pi3, and so on).

[0009] According to the invention, the apparatus has a detection device adapted to detect at least one characteristic value of a plastic container, wherein the duration of the pressurization time for at least one intermediate blow molding pressure can be adjusted based on this characteristic value of the plastic container. Preferably, the duration of the pressurization time is automatically adjusted based on the characteristic value of the plastic container. The pressurization time for the intermediate blow molding pressure refers to a period of time during which an intermediate blow molding pressure is applied to the plastic container. The shorter this pressurization time, the earlier the final blow molding pressure can be applied. However, the longer this pressurization time, the more pressurized air can be recycled and used for the next molding process.

[0010] Accordingly, it is proposed that, with the aid of a detection device, such as a camera device already present on existing equipment as appropriate, the optimal setting of the intermediate blow molding pressure rise time be determined, and the regulating device be controlled (fully)automatically accordingly. The optimal setting achieves good quality plastic containers while minimizing pressurized air consumption.

[0011] In principle, the equipment aims to achieve a certain pressurization time so that the so-called efficiency (a calculated value visualized on the operator's terminal (HMI), which reflects the efficiency of air recovery (pressurized air recycling) in the two intermediate blow molding stages) reaches exactly 100%. However, once the container quality falls below a critical level, the regulator value is no longer allowed to be increased, meaning the pressurization time cannot be further extended, even if optimal recycling has not yet been achieved. Therefore, container quality takes precedence over recycling volume.

[0012] Accordingly, the aim is to find a compromise or setting that balances good container quality with the shortest possible pressurization time and the minimum pressurization air consumption in a preferred automated manner.

[0013] Therefore, as described above, characteristic values ​​of plastic containers are measured, and preferably characteristic values ​​of plastic containers formed by the device are measured.

[0014] The characteristic values ​​are then transmitted to an evaluation system (evaluation device), which determines the quality of the plastic container. If the container quality is good, the regulating device is preferably adjusted or controlled in a way that reduces the pressurization time. If the container quality is poor, the regulating device is preferably adjusted or controlled in a way that extends the pressurization time. This operation can be repeated until sufficient container quality is achieved while minimizing pressurized air consumption. Advantageously, the settings of the regulating device, including the values ​​of the pressurization time and the characteristic values ​​of the container quality, can be stored in a storage device. These stored values ​​can be selected the next time this type of container is manufactured.

[0015] The regulating device preferably adjusts the duration of the pressurization time accordingly, which is the duration of applying intermediate blow molding pressure to the plastic container.

[0016] Therefore, in a preferred embodiment, the device has an evaluation device adapted and used to evaluate and / or assess at least one characteristic value detected by the detection device for the plastic container, thereby inferring the quality of the plastic container. Preferably, a control loop can be implemented therein, wherein the detection device and / or the evaluation device assesses the quality of the bottle, such as turbidity caused by stress whitening on the bottle sidewalls or bottom.

[0017] In another preferred embodiment, the evaluation device is adapted and used to compare at least one characteristic value of a plastic container detected by the detection device with preset and / or stored values. Preferably, the actual value (the detected characteristic value) is compared with a nominal value (the stored value). Preferably, the at least one characteristic value or actual value of the plastic container detected by the detection device is compared with a preset and / or stored range, specifically determining whether the characteristic value is within the preset range. The characteristic value may be, for example, the surface characteristics of the plastic container (color, turbidity, roughness), the diameter or other dimensions of the container, or something similar.

[0018] Therefore, the device preferably includes a storage device storing a large number of preset feature values ​​and / or ranges for the plastic container. Preferably, the feature values ​​may also be images or feature images of the plastic container. In this case, the detection device is preferably a camera-like imaging device that detects or captures images of the plastic container. The preset values ​​and / or ranges are preferably parameters preset for the finished plastic container, which are selected or input by an operator on an operating terminal. Preferably, the pressurization time can also be determined based on these preset parameters for the finished plastic container.

[0019] Accordingly, the storage device is preferably also adapted and used to store images, and the evaluation device is adapted to compare the feature images captured by the detection device with the images stored in the storage device.

[0020] In a preferred embodiment, the detected value is compared with a nominal value (big data) preferably stored in the cloud. This can be values ​​from different machines serving different clients, provided to the cloud.

[0021] As described above, the adjusting device is then set according to this characteristic value reflecting the quality of the plastic container, and the adjusting device further adjusts the pressurization time. In a preferred embodiment, the adjusting device is steplessly movable between a minimum and a maximum pressurization time. The minimum and maximum pressurization times are fixedly preset by the device. Preferably, the adjusting device includes a sliding adjuster located on a graphical user interface, such as the device's operating terminal. Until now, the position of the sliding adjuster has required manual setting. This invention proposes to automatically set or adjust the position of the sliding adjuster according to the container quality.

[0022] The evaluation device is preferably an AI (artificial intelligence) or a computing unit that evaluates the feature values ​​and controls or sets the adjustment device accordingly. The AI ​​or computing unit can be locally connected to the device. However, the AI ​​or computing unit is preferably wirelessly connected to the device. Particularly preferably, an artificial neural network is used as the AI, trained through supervised learning to guide the system to make desired adjustments in the face of process fluctuations. Here, specific results are preset for different input schemes. Based on continuous comparison of nominal and actual results, the network learns to connect neurons in a matching manner. However, unsupervised learning, reinforcement learning, or random learning can also be used to train the artificial neural network.

[0023] Blowing pressure is applied to the plastic container during the pre-blowing stage and the molding stage, wherein a pre-blowing pressure is applied to the plastic container during the pre-blowing stage, and at least one, preferably two, intermediate blowing pressures and a final blowing pressure are applied to the plastic container during the molding stage.

[0024] The pre-blow pressure is applied to the plastic container for at least 100 ms, preferably at least 110 ms, and particularly preferably at least 115 ms. Preferably, the at least one intermediate blow molding pressure and the final blow molding pressure are applied to the plastic container for at least 250 ms, preferably at least 265 ms, and particularly preferably at least 280 ms. The timing of applying the final blow molding pressure preferably depends on the intensification time of the intermediate blow molding pressure.

[0025] In a preferred embodiment, the device has a valve configuration that controls the application of the pre-blow pressure, the at least one and preferably two intermediate blow pressures, and the final blow pressure to the plastic container.

[0026] As described above, the apparatus for forming plastic preforms into plastic containers is preferably a blow molding apparatus or a molding station. The blow molding apparatus preferably consists of multiple parts and has two blow molding mold halves and a bottom mold. Preferably, these blow molding halves are detachably arranged on a mold housing or a blow molding bracket. The blow molding bracket rotates relative to each other to open and close the blow molding apparatus. Furthermore, the blow molding bracket has a locking mechanism to lock the halves together during the blow molding process.

[0027] Preferably, the plastic preform is expanded into a plastic container by applying pressurized air. For this purpose, the apparatus preferably includes an application device and an air nozzle that can be brought into contact with the opening of the plastic preform to apply pressurized air to the preform or to expand it using pressurized air.

[0028] Particularly preferably, the application device, and in particular the blowing piston and / or blowing nozzle, is movable longitudinally along the plastic container and / or toward the plastic container.

[0029] In an advantageous embodiment, the blow molding apparatus or molding station each has tension bars that stretch the plastic preform longitudinally. Particularly preferably, the blow molding machine or carrier and molding station are arranged within a cleanroom that defines the boundary of the blow molding machine relative to a non-sterile environment. Drive mechanisms for closing, locking, and / or opening the blow molding die are preferably located outside the cleanroom.

[0030] The blow molding apparatus is preferably transported within a cleanroom, which is preferably separated by multiple walls. Here, the cleanroom is preferably defined by at least one fixed wall and a movable wall relative to that fixed wall. In this case, for example, the transport bracket on which the blow molding apparatus is mounted may already have or form one of these walls, particularly the movable wall. The cleanroom separates the blow molding apparatus from a non-sterile environment.

[0031] The present invention also relates to a method for molding a plastic preform into a plastic container, wherein the plastic preform to be molded is transported along a preset conveying path, wherein a plurality of molding stations are provided on a rotatable transport carrier, wherein each molding station has a blow molding device in which the plastic preform is molded into a plastic container, wherein each molding station has an application device that applies a flowable medium and, in particular, pressurized air to the plastic preform, wherein the application device applies a pre-blow pressure, at least one and preferably two intermediate blow molding pressures, and a final blow molding pressure to the plastic preform, and wherein an adjusting device adjusts the duration of the pressurization time of at least one intermediate blow molding pressure.

[0032] According to the present invention, at least one characteristic value of a plastic container is detected, wherein the duration of the pressurization time of at least one intermediate blow molding pressure is adjusted based on this characteristic value of the plastic container.

[0033] Accordingly, in terms of method, it is also proposed to determine the optimal setting of the pressurization time of the intermediate blow molding pressure, and in particular to control the regulating device (fully) automatically according to the characteristic values ​​of the plastic container.

[0034] In a preferred method, at least one feature value of the plastic container is compared with preset and / or stored values. Preferably, the feature value may also be a feature image of the plastic container or an image of the plastic container, wherein the feature image is compared with a stored image. Preferably, the feature value or feature image reflects the quality characteristics of the plastic container.

[0035] The apparatus described above is also specifically configured and used to implement the method, meaning that all features detailed in the description of the apparatus are also disclosed in connection with the method described herein, and vice versa.

[0036] For more advantages and implementation methods, please refer to the accompanying drawings. Attached Figure Description

[0037] Figure 1 A schematic diagram of an apparatus for forming a plastic preform into a plastic container; Figure 2 For blow molding characteristic curves; and

[0038] Figure 3 This is an example of setting up the molding process.

[0039] List of icon numbers

[0040] 1 device

[0041] 2. Transport equipment

[0042] 2a Circular Channel

[0043] 4 Molding Station

[0044] 7. Pressure supply device

[0045] 8 Cleanroom

[0046] 10 Plastic Preform

[0047] 15 Plastic containers

[0048] 22 transport brackets

[0049] 30 stretch units

[0050] 50 Adjustment Device

[0051] 52 Detection Device

[0052] 54 Evaluation Device

[0053] 55 storage devices

[0054] 62 Feeding device

[0055] 64 Discharge Device

[0056] 72 First connecting line

[0057] 74 Rotary Distributor

[0058] 76 Second connecting line

[0059] 82 blow molding unit

[0060] 84 Application device

[0061] 88 tension bar

[0062] 90 valve configuration

[0063] 98 Third Connector

[0064] 100 Operating Terminal

[0065] 105 monitor

[0066] 110 Blow Molding Characteristic Curve

[0067] Arrow A

[0068] Ap molding stage

[0069] Vp pre-blow molding stage

[0070] P1 pressure, pre-blowing pressure

[0071] Pi pressure, Pi, intermediate blow molding pressure

[0072] Pi2 pressure, intermediate blow molding pressure

[0073] P2 pressure, final blow molding pressure

[0074] Characteristic curve of Rv tension bar Detailed Implementation

[0075] Figure 1 An apparatus 1 for molding a plastic preform 10 into a plastic container 15 is shown. This apparatus 1 has a rotatable carrier 22 on which several molding stations 4 are provided. Each molding station 4 has a blow molding device 82, which forms a cavity inside for the expansion of the plastic preform.

[0076] Reference numeral 84 indicates an application device for expanding the plastic preform 10. Reference numeral 90 indicates a valve configuration, such as a valve assembly, preferably having a large number of valves that control the application of pressure to the plastic preform at different pressure levels.

[0077] In a preferred method, a pre-blowing pressure P1 is first applied to the plastic preform, followed by at least one intermediate blow molding pressure Pi higher than the pre-blowing pressure, and finally a final blow molding pressure P2 higher than the intermediate blow molding pressure Pi. After the plastic container expands, the pressure or pressurized air is preferably returned from the container to the accumulators.

[0078] Reference numeral 88 indicates a stretching rod for stretching the plastic preform longitudinally, and reference numeral 30 indicates a stretching unit for controlling the movement of the stretching rod. Preferably, all molding stations have such a blow mold 82 and a stretching rod 88. Preferably, the number of these molding stations is between 2 and 100, more preferably between 4 and 60, and even more preferably between 6 and 40.

[0079] The plastic preform 10 is fed to the device via the feeding device 62 (especially the conveyor star wheel, but not limited thereto), and the molded plastic container 15 is discharged via the discharging device 64.

[0080] Reference numeral 7 indicates a pressure supply device, such as a booster or pressurized air connector. Pressurized air is supplied to a rotary distributor 74 via a first connecting line 72, and released from this rotary distributor to an annular channel 2a via a second connecting line 76.

[0081] In addition to the annular channel 2a shown, other annular channels are preferably provided, but they are in Figure 1 The view shown is obscured by annular channel 2a, for example, arranged below. Preferably, several annular channels overlap each other. Reference numeral 98 indicates a third connecting line for releasing pressurized air to molding station 4 or its valve configuration 90. Preferably, each of the annular channels is connected to all molding stations via a corresponding connecting line.

[0082] Reference numeral 8 schematically represents a cleanroom, which is preferably annular and surrounds the transport path of the plastic preform 10. Preferably, a (geometric) rotating axis is arranged on the outside of the cleanroom 8, relative to which the transport vehicle can rotate. Preferably, the cleanroom is isolated from non-sterile environments by a sealing device, preferably having at least two pressure reservoirs.

[0083] Reference numeral 52 indicates a detection device used to detect feature values, such as an image of a plastic container. This detection device can also be located at the position of device 1. As shown by the dashed lines, the detected feature values ​​or the detected feature image are preferably transmitted wirelessly to an evaluation device 54, which evaluates the image or compares it with values ​​stored in a storage device 55 as described above. Reference numeral 50 indicates an adjustment device, here for example a shift register, which is adjusted according to the evaluation results.

[0084] Figure 2 This is a graph of the blow molding characteristic curve 110. The reference numeral Vp indicates the pre-blow molding stage, during which a pre-blow pressure P1 is applied. The molding stage Ap is shown as a dashed line, where the final blow molding pressure P2 is applied in the area within the solid line but within the dashed line, and intermediate blow molding pressures Pi and Pi2 are applied in the area to the left of the solid line (between the solid and dashed lines). After applying the final blow molding pressure P2, this final blow molding pressure is maintained for a certain period. The pressurized air used is then recycled, and the container is depressurized, as can be seen from the descent curve. The reference numeral Rv indicates the characteristic curve of the tension bar.

[0085] Figure 3 An example setup of the molding process is shown. Specifically, the values ​​are illustrated here on the operating terminal 100 of the device. Specifically, values ​​such as... Figure 2 The characteristic curves shown are shown.

[0086] from Figure 2 x-axis and Figure 3 As can be seen from display 105, the pre-blow molding stage Vp starts at 230ms and lasts for 115ms, so the molding stage Ap starts at 345ms and lasts for 280ms, so it ends at 625ms.

[0087] In the figure, reference numeral 50 indicates an adjusting device, such as a sliding adjuster that can be moved as shown by arrow A. This adjusting device is configured such that the application time of intermediate blow molding pressures Pi and Pi2 is 90 ms, thus achieving a process efficiency of up to 99%. Preferably, the position of this adjusting device is automatically adjusted and modified by the method or device described above, particularly according to the characteristic values ​​and / or quality of the plastic container.

[0088] The applicant reserves the right to claim all features disclosed in the application documents as fundamental features of the invention, provided that these features, individually or in combination, are novel compared to the prior art. Furthermore, it should be noted that features that may be advantageous in themselves are also described in individual figures. It will be immediately apparent to a person skilled in the art that a particular feature described in a figure may be advantageous, even without employing other features in that figure. Additionally, a person skilled in the art will recognize that advantages can also be derived by combining several features shown in a single figure or different figures.

Claims

1. An apparatus (1) for molding a plastic preform (10) into a plastic container (15), comprising a transport device (2) that transports the plastic preform (10) to be molded along a preset transport path, wherein, The transport device (2) has a rotatable transport carrier (22) on which a plurality of molding stations (4) are provided. Each molding station has a blow molding device (82) in which a plastic preform (10) can be molded into a plastic container (15). Each molding station (4) has an application device (84) that applies a flowable medium to the plastic preform (10). The application device applies a pre-blow pressure (P1), at least one intermediate blow molding pressure (Pi, Pi2), and a final blow molding pressure (P2) to the plastic preform (10). The device also has an adjustment device (50) that is adapted to and used to adjust the duration of the pressurization time of at least one intermediate blow molding pressure (Pi, Pi2). Its features are, The device (1) has a detection device (52) adapted to and used to detect at least one characteristic value of the plastic container (15), wherein the duration of the pressurization time of at least one intermediate blow molding pressure (Pi, Pi2) can be adjusted according to the characteristic value of the plastic container (15). The device (1) has an evaluation device (54) adapted and used to evaluate and / or assess at least one characteristic value detected by the detection device (52) for the plastic container (15), thereby inferring the quality of the plastic container (15); The evaluation device (54) is adapted and used to compare the at least one feature value of the plastic container (15) detected by the detection device (52) with a preset and / or stored value.

2. The apparatus (1) according to claim 1. Its features are, The detected value is compared with the nominal value.

3. The apparatus (1) according to claim 1. Its features are, The regulating device (50) is capable of steplessly moving between the minimum and maximum values ​​of the boost time.

4. The apparatus (1) according to claim 1. Its features are, The detection device (52) is a camera.

5. The apparatus (1) according to claim 4, characterized in that, The shooting device is a camera.

6. The apparatus (1) according to claim 1. Its features are, The device (1) has a valve configuration (90) that controls the application of the pre-blow pressure (P1), the at least one intermediate blow pressure (Pi, Pi2) and the final blow pressure (P2) to the plastic container (15).

7. A method for molding a plastic preform (10) into a plastic container (15), wherein, The plastic preform (10) to be formed is transported along a preset conveying path, wherein multiple forming stations (4) are provided on a rotatable transport carrier (22), wherein each forming station has a blow molding device (82), in which the plastic preform (10) is formed into a plastic container (15), wherein each forming station (4) has an application device (84), the application device applies a flowable medium to the plastic preform (10), wherein the application device applies a pre-blow pressure (P1), at least one intermediate blow molding pressure (Pi, Pi2), and a final blow molding pressure (P2) to the plastic preform (10), and an adjusting device adjusts the duration of the pressurization time of at least one intermediate blow molding pressure (Pi, Pi2). Its features are, Detect at least one characteristic value of the plastic container (15), wherein the duration of the pressurization time of at least one intermediate blow molding pressure (Pi, Pi2) is adjusted according to the characteristic value of the plastic container (15); The at least one characteristic value of the plastic container (15) is compared with a preset and / or stored value.

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